A Consecutive Priming-Boosting Vaccination of Mice with Simian Immunodeficiency Virus (SIV) gag/pol DNA and Recombinant Vaccinia Virus Strain DIs Elicits Effective Anti-SIV Immunity

Abstract

ABSTRACT To evaluate immunity induced by a novel DNA prime-boost regimen, we constructed a DNA plasmid encoding the gag and pol genes from simian immunodeficiency virus (SIV) (SIV gag/pol DNA), in addition to a replication-deficient vaccinia virus strain DIs recombinant expressing SIV gag and pol genes (rDIsSIV gag/pol ). In mice, priming with SIV gag/pol DNA, followed by rDIsSIV gag/pol induced an SIV-specific lymphoproliferative response that was mediated by a CD4 + -T-lymphocyte subset. Immunization with either vaccine alone was insufficient to induce high levels of proliferation or Th1 responses in the animals. The prime-boost regimen also induced SIV Gag-specific cellular responses based on gamma interferon secretion, as well as cytotoxic-T-lymphocyte responses. Thus, the regimen of DNA priming and recombinant DIs boosting induced Th1-type cell-mediated immunity, which was associated with resistance to viral challenge with wild-type vaccinia virus expressing SIV gag/pol , suggesting that this new regimen may hold promise as a safe and effective vaccine against human immunodeficiency virus type 1.